Biological reductive dechlorination can be used to remediate aquifers contaminated with chlorinated solvents.
This process can be stimulated with the addition of hydrogen as an electron donor. A small field
study was conducted in a trichloroethene (TCE)-contaminated aquifer at the Twin Cities Army Ammunition
Plant site in Arden Hills, MN, to determine whether hollow-fiber membranes could be used to deliver
hydrogen to the contaminated groundwater to stimulate bioremediation in situ. Nonporous silicone-coated
membranes were placed in Geoprobe wells, where they were able to sustain hydrogen delivery
over 20 months without a decline in gas transfer performance. High concentrations of hydrogen (168 ±
13 µM) were observed in the wells containing membrane modules. These concentrations were similar to
that predicted using a clean water gas transfer gas correlation (255 µM). High acetate concentrations
(662 ± 172 µM) were also observed in the wells containing membrane modules during hydrogen addition.
The addition of hydrogen via the hollow-fiber membranes stimulated vinyl chloride and ethene formation,
likely as a result of the activity of acetotrophic dechlorinators.
